Methods for treating semiconductor substrates

ABSTRACT

The invention includes a method for treating a plurality of discrete semiconductor substrates. The discrete semiconductor substrates are placed within a reactor chamber. While the substrates are within the chamber, they are simultaneously exposed to one or more of H, F and Cl to remove native oxide. After removing the native oxide, the substrates are simultaneously exposed to a first reactive material to form a first mass across at least some exposed surfaces of the substrates. The first reactive material is removed from the reaction chamber, and subsequently the substrates are exposed to a second reactive material to convert the first mass to a second mass. The invention also includes apparatuses which can be utilized for simultaneous ALD treatment of a plurality of discrete semiconductor substrates.

TECHNICAL FIELD

The invention pertains to methods for treating pluralities of discretesemiconductor substrates to form layers of material over the substrates.In particular applications, the invention pertains to atomic layerdeposition of materials over semiconductor substrates. The inventionalso pertains to apparatuses which can be utilized during treatment of aplurality of discrete semiconductor substrates.

BACKGROUND OF THE INVENTION

It is frequently desired to form high quality layers of material oversemiconductor substrates during semiconductor device fabrication. Amongthe materials which can be included in such layers are tantalumpentoxide, titanium nitride, titanium silicon nitride, tantalum nitride,tantalum silicon nitride, titanium silicide, tantalum silicide, tungstennitride, aluminum oxide, hafnium oxide, zirconium oxide, siliconnitride, silicon dioxide, elemental tungsten and elemental titanium.Numerous methods have been developed for forming layers of suchmaterials, with exemplary methods including chemical vapor deposition(CVD), and in some cases atomic layer deposition (ALD).

Chemical vapor deposition comprises mixing two or more reactants in achamber to form a material which subsequently deposits across exposedsurfaces of one or more semiconductor substrates. An advantage ofchemical vapor deposition is that it can be utilized in batch processes,or, in other words, can be utilized to simultaneously treat a pluralityof discrete semiconductor substrates. Among the disadvantages ofchemical vapor deposition is that it can be difficult to controlreactions between the reactants provided in a chamber, and accordinglyvarious side-reactions can occur to generate contaminants. Additionally,it can be difficult to form a uniform layer over multiple exposedsurfaces of one or more semiconductor substrates with CVD. Thedeposition of CVD material can be faster in various regions ofsemiconductor typography than other regions, leading to non-uniformityin a thickness of the deposited material across various exposed surfacesof semiconductor substrates provided within a CVD reaction chamber.

ALD can overcome some of the problems discussed above relative to CVD.ALD processing typically comprises forming thin films of material byrepeatedly depositing monoatomic layers. The technique involvesindividually depositing precursors, or reactants, that react in situ toform a desired film of material across a semiconductor substrate. Morespecifically, ALD processes involve introduction of a first reactantwhich reacts with a substrate to form a monolayer across the substrate.The first reactant will typically react with the substrate, but not withitself. Accordingly, side-reactions are eliminated. Further, thereaction of the reactant with the substrate is self-limiting, in thatonce a monolayer forms across exposed surfaces of the substrate there isno longer further reaction of the reactant with the substrate.

After the monolayer is formed, the first reactant is flushed from theprocessing chamber, and a second reactant is subsequently introduced.The second reactant reacts with the monolayer of material formed fromthe first reactant to convert such monolayer into a desired mass overthe substrate. The desired mass can be uniformly thick across thevarious surfaces of the substrate. The mass can be made thicker byrepeating the above-described process. Specifically, the mass can becomean upper surface of a semiconductor substrate, and can be utilized forreaction with the first reactant. Subsequently, the second reactant canbe introduced to form a second layer of the mass over the first layer.The process can be repeated until a desired thickness of the mass isformed.

A problem with existing ALD technologies is that such are not typicallysuitable for utilization in batch processes. Rather, semiconductorsubstrates are treated one at a time, and throughput of substratesthrough ALD processes is thus low relative to CVD processes. Some efforthas recently been made to develop batch processes for ALD of siliconnitride. Specifically, a batch of wafers is exposed to trichlorosilanein a reaction chamber to form a silicon-containing monolayer overexposed surfaces of the substrates. Subsequently, the trichlorosilane isevacuated from the chamber and ammonia is introduced to convert thesilicon-containing material to silicon nitride. The trichlorosilanedeposition occurs at a temperature at least 150° C. different than theammonia treatment.

It would desirable to extend batch ALD processes to other materialsbesides silicon nitride. It would also be desirable to develop improvedprocesses for batch ALD of silicon nitride.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a method for treating aplurality of discrete semiconductor substrates. The discretesemiconductor substrates are placed within a reactor chamber. While thesubstrates are within the chamber, they are simultaneously exposed toone or more of H, F and Cl to remove native oxide (such can beconsidered an in situ cleaning of the substrates). After removing thenative oxide, the substrates are simultaneously exposed to a firstreactive material to form a first mass across at least some exposedsurfaces of the substrates. The first reactive material is removed fromthe reaction chamber, and subsequently the substrates are exposed to asecond reactive material to convert the first mass to a second mass.

In one aspect, the invention encompasses a method in which a pluralityof discrete semiconductor substrates are placed within a reactionchamber and simultaneously exposed to a first reactive material to forma first mass across at least some exposed surfaces of the substrates.The first reactive material is removed from the reaction chamber, andsubsequently the substrates are exposed to a second reactive material toconvert the first mass to a second mass. The second mass comprises oneor more of tantalum, titanium, tungsten, aluminum, hafnium, SiO and Zr,with the listed composition of SiO being shown in terms of the elementscontained therein rather than in terms of a stoichiometric relationshipwith the elements.

In one aspect, the invention encompasses a method in which a pluralityof discrete semiconductor substrates are treated within a reactionchamber. The substrates are first exposed to a first reactive materialto form a first mass across at least some exposed surfaces of thesubstrates, with the substrates being held at a first temperature duringthe exposure to the first reactive material. The first reactive materialis then removed from the reaction chamber. Next, the substrates areexposed to a second reactive material to convert the first mass to asecond mass, with the substrates being at a temperature within about100° C. of the first temperature during the exposing to the secondreactive material. It is noted that in particular aspects of theinvention, the temperature of the substrates during exposure to thefirst reactive material can vary by more than 100° C. relative to thetemperature of the substrates during exposure to the second reactivematerial.

Various aspects of the invention can utilize a fast ramp furnace tocontrol the temperature of substrates exposed to reactive materials, andthe purging of reactive materials from a reaction chamber can occurduring ramp-up and/or ramp-down of the temperature of substrates withinthe chamber.

Various aspects of the invention can utilize remote assisted chemicalactivated methodologies to enhance atomic layer deposition. For example,plasma-assist and/or pre-heating of materials can be utilized inmethodology of the present invention.

In one aspect, the invention encompasses apparatuses which can beutilized for treating a plurality of discrete semiconductor substrates.The apparatuses can be particularly well suited for atomic layerdeposition.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic, cross-sectional view of a semiconductor waferfragment shown at a preliminary processing step of an exemplary methodof the present invention.

FIG. 2 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 1.

FIG. 3 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 2.

FIG. 4 is a diagrammatic, cross-sectional view of a reaction chamberwhich can be utilized in various methods associated with the presentinvention. The reaction chamber is shown at an exemplary processingstep, and accordingly has a plurality of discrete semiconductorsubstrates shown therein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In particular aspects, the present application pertains to atomic layerdeposition (ALD) technology. ALD technology typically involves formationof successive atomic layers on a substrate. Such layers may comprise,for example, an epitaxial, polycrystalline, and/or amorphous material.ALD may also be referred to as atomic layer epitaxy, atomic layerprocessing, etc.

The deposition methods herein are described in the context of formationof materials on one or more semiconductor substrates. In the context ofthis document, the term “semiconductor substrate” or “semiconductivesubstrate” is defined to mean any construction comprising semiconductivematerial, including, but not limited to, bulk semiconductive materialssuch as a semiconductive wafer (either alone or in assemblies comprisingother materials thereon), and semiconductive material layers (eitheralone or in assemblies comprising other materials). The term “substrate”refers to any supporting structure, including, but not limited to, thesemiconductive substrates described above. Also in the context of thepresent document, “metal” or “metal element” refers to the elements ofGroups IA, IIA, and IB to VIIIB of the periodic table of the elementsalong with the portions of Groups IIIA to VIA designated as metals inthe periodic table, namely, Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Bi, and Po.The Lanthanides and Actinides are included as part of Group IIIB.“Non-metals” refers to the remaining elements of the periodic table.

Described in summary, ALD includes exposing an initial substrate to afirst chemical species to accomplish chemisorption of the species ontothe substrate. Theoretically, the chemisorption forms a monolayer thatis uniformly one atom or molecule thick on the entire exposed initialsubstrate. In other words, a saturated monolayer. Practically, asfurther described below, chemisorption might not occur on all portionsof the substrate. Nevertheless, such an imperfect monolayer is still amonolayer in the context of this document. In many applications, merelya substantially saturated monolayer may be suitable. A substantiallysaturated monolayer is one that will still yield a deposited layerexhibiting the quality and/or properties desired for such layer.

The first species is purged from over the substrate and a secondchemical species is provided to chemisorb onto the first monolayer ofthe first species. The second species is then purged and the steps arerepeated with exposure of the second species monolayer to the firstspecies. In some cases, the two monolayers may be of the same species.Also, a third species or more may be successively chemisorbed and purgedjust as described for the first and second species. It is noted that oneor more of the first, second and third species can be mixed with inertgas to speed up pressure saturation within a reaction chamber.

Purging may involve a variety of techniques including, but not limitedto, contacting the substrate and/or monolayer with a carrier gas and/orlowering pressure to below the deposition pressure to reduce theconcentration of a species contacting the substrate and/or chemisorbedspecies. Examples of carrier gases include N₂, Ar, He, Ne, Kr, Xe, etc.Purging may instead include contacting the substrate and/or monolayerwith any substance that allows chemisorption byproducts to desorb andreduces the concentration of a species preparatory to introducinganother species. A suitable amount of purging can be determinedexperimentally as known to those skilled in the art. Purging time may besuccessively reduced to a purge time that yields an increase in filmgrowth rate. The increase in film growth rate might be an indication ofa change to a non-ALD process regime and may be used to establish apurge time limit.

ALD is often described as a self-limiting process, in that a finitenumber of sites exist on a substrate to which the first species may formchemical bonds. The second species might only bond to the first speciesand thus may also be self-limiting. Once all of the finite number ofsites on a substrate are bonded with a first species, the first specieswill often not bond to other of the first species already bonded withthe substrate. However, process conditions can be varied in ALD topromote such bonding and render ALD not self-limiting. Accordingly, ALDmay also encompass a species forming other than one monolayer at a timeby stacking of a species, forming a layer more than one atom or moleculethick. The various aspects of the present invention described herein areapplicable to any circumstance where ALD may be desired. It is furthernoted that local chemical reactions can occur during ALD (for instance,an incoming reactant molecule can displace a molecule from an existingsurface rather than forming a monolayer over the surface). To the extentthat such chemical reactions occur, they are generally confined withinthe uppermost monolayer of a surface.

Traditional ALD can occur within an frequently-used ranges oftemperature and pressure and according to established purging criteriato achieve the desired formation of an overall ALD layer one monolayerat a time. Even so, ALD conditions can vary greatly depending on theparticular precursors, layer composition, deposition equipment, andother factors according to criteria known by those skilled in the art.Maintaining the traditional conditions of temperature, pressure, andpurging minimizes unwanted reactions that may impact monolayer formationand quality of the resulting overall ALD layer. Accordingly, operatingoutside the traditional temperature and pressure ranges may riskformation of defective monolayers.

The general technology of chemical vapor deposition (CVD) includes avariety of more specific processes, including, but not limited to,plasma enhanced CVD and others. CVD is commonly used to formnon-selectively a complete, deposited material on a substrate. Onecharacteristic of CVD is the simultaneous presence of multiple speciesin the deposition chamber that react to form the deposited material.Such condition is contrasted with the purging criteria for traditionalALD wherein a substrate is contacted with a single deposition speciesthat chemisorbs to a substrate or previously deposited species. An ALDprocess regime may provide a simultaneously contacted plurality ofspecies of a type or under conditions such that ALD chemisorption,rather than CVD reaction occurs. Instead of reacting together, thespecies may chemisorb to a substrate or previously deposited species,providing a surface onto which subsequent species may next chemisorb toform a complete layer of desired material.

Under most CVD conditions, deposition occurs largely independent of thecomposition or surface properties of an underlying substrate. Bycontrast, chemisorption rate in ALD might be influenced by thecomposition, crystalline structure, and other properties of a substrateor chemisorbed species. Other process conditions, for example, pressureand temperature, may also influence chemisorption rate. Accordingly,observation indicates that chemisorption might not occur appreciably onportions of a substrate though it occurs at a suitable rate on otherportions of the same substrate. Such a condition may introduceintolerable defects into a deposited material.

An exemplary ALD process is described with reference to FIGS. 1–3.Referring initially to FIG. 1, a semiconductor construction 10 isillustrated. Construction 10 comprises a semiconductor substrate 12.Substrate 12 can comprise, for example, a monocrystalline silicon havingone or more materials (not shown) supported thereby. In particularapplications, substrate 12 can comprise a monocrystalline silicon waferthat is ultimately to have various integrated circuit devices formedthereover. The devices can be at various stages of completion in theprocessing of FIG. 1. The various devices which can be associated withsubstrate 12 will be recognized by persons of ordinary skill in the art,and are not shown in the diagrammatic illustration of FIG. 1.

Referring to FIG. 2, construction 10 is shown at a processing stepsubsequent to that of FIG. 1. Specifically, the construction isillustrated after a monolayer 14 has been formed across substrate 12.Monolayer 14 can be formed by placing construction 10 within a reactionchamber, and exposing the construction to a suitable ALD reactant togenerate the monolayer 14. After monolayer 14 is formed, the reactionchamber can be purged of the reactant utilized to generate themonolayer. Subsequently, a second reactant can be introduced to convertmonolayer 14 into a desired mass 16, which is illustrated in FIG. 3. Insubsequent cycles, the combined mass 16 and substrate 12 can beconsidered a new substrate for ALD deposition, and subjected to theprocessing described with reference to FIGS. 2 and 3 to increase athickness of mass 16. Alternatively, or additionally, mass 16 can besubjected to a third reactant to convert the mass to yet another desiredmaterial.

In exemplary processing, mass 16 can comprise one or more of TaO, TiN,TiSiN, TaSiN, TaSi, TaN, WN, W, Ti, Al, O, HfO, ZrO, SiO, SiN, TiSi, andWSi; with the listed compositions being shown in terms of the elementscontained therein rather than in terms of a stoichiometric relationshipof the elements. Accordingly, the indicated SiO can be in the form ofsilicon dioxide (SiO₂), and the indicated SiN can be in the form ofsilicon nitride (Si₃N₄). In further particular embodiments, the mass 16can consist of, or consist essentially of, TaO, TiN, TiSiN, TaSiN, TaSi,TaN, WN, W, Ti, AlO, HfO, ZrO, SiO, SiN, TiSi, WSi, and SiON; with thelist of compositions being shown in terms of the elements containedtherein, rather than in terms of a stoichiometric relationship with theelements.

Mass 16 can be exposed to post-formation processing to convert the massto another material. For instance, if mass 16 comprises SiN, the masscan be exposed to oxygen to form SiON from the SiN (with the compositionSiON being shown in terms of the elements contained therein, rather thanin terms of a stoichiometric relationship with the elements). Theexposure to oxygen can comprise exposure to one or more of O₂, O₃, andH₂O₂.

Numerous methods can be utilized for forming various of theabove-described materials of mass 16. In an exemplary method, mass 16comprises Ta₂O₅. Such mass can be formed utilizing a first reactivematerial comprising, consisting essentially of, or consisting oftantalum pentaethoxide to generate the first mass 14 (FIG. 2), and thenutilizing a second reactive material comprising, consisting essentiallyof, or consisting of ozone to convert the first mass 14 to the secondmass 16 (FIG. 3) of Ta₂O₅.

In another exemplary embodiment, a first reactive material comprising,consisting essentially of, or consisting of TiCl₄ is utilized togenerate first mass 14, and a second reactive material comprising,consisting essentially of, or consisting of NH₃ is utilized to convertfirst mass 14 into a second mass 16 comprising TiN.

In another exemplary embodiment, the first reactive material cancomprise, consist essentially of, or consist of TiCl₄ and be utilized togenerate the first mass 14, and such can subsequently be exposed to asecond reactive material which contains silicon to generate second mass16 comprising, consisting essentially of, or consisting of Ti and Si.Such mass 16 can be referred to as comprising Ti_(t)Si_(x), with t and xbeing greater then 0. The silicon-containing reactive material cancomprise, consist essentially of, or consist of, for example, silane. Infurther processing, the mass 16 can be exposed to a third reactivematerial comprising NH₃ to convert the mass to Ti_(t)Si_(x)N_(y), witht, x and y being greater than 0. Alternatively, the second reactivematerial can comprise H₂O, and mass 16 can comprise TiO₂.

In further exemplary processing, a first reactive material comprising,consisting essentially of, or consisting of TaCl₅ can be utilized togenerate first mass 14, and such can subsequently be exposed to a secondreactive material comprising silicon to form the second mass 16comprising, consisting essentially of, or consisting of Ta and Si. Thesilicon-containing material can comprise, consist essentially of, orconsist of, for example, silane. The mass comprising Ta and Si can be,for example, Ta_(t)Si_(x), where t and x are greater than 0. In furtherprocessing, the mass comprising Ta and Si can be exposed to a reactivematerial comprising, consisting essentially of, or consisting of NH₃ toconvert the mass to Ta_(t)Si_(x)N_(y), with t, x and y being greaterthan 0.

In yet other exemplary processing, the first reactive material cancomprise, consist essentially of, or consist of WF₆ to form the firstmass 14, and such mass can then be exposed to a second reactive materialcomprising silicon to generate the second mass 16 comprising, consistingessentially of, or consisting of W_(t)Si_(x), with t and x being greaterthan 0. The silicon-containing reactive material can comprise, consistessentially of, or consist of, for example, silane.

In yet other exemplary processing, the first reactive material cancomprise, consist essentially of, or consist of TaF₅ and be utilized togenerate first mass 14. The first mass can then be exposed to a secondreactive material comprising, consisting essentially of, or consistingof NH₃, to form the second mass 16 comprising, consisting essentiallyof, or consisting of Ta_(t)N_(x), with t and x being greater than 0.

In yet other exemplary processing, the first reactive material cancomprise WF₆ to generate the first mass 14. The first mass 14 can thenbe exposed to a second reactive material comprising, consistingessentially of, or consisting of NH₃ to generate the second mass 16comprising W_(t)N_(x), with t and x being greater than 0. Alternatively,the second reactive material can comprise, consist essentially of, orconsist of H₂, to generate the second mass 16 comprising, consistingessentially of, or consisting of W.

In yet other exemplary processing, the mass 16 can comprise, consistessentially of, or consist of Ti; and can be formed from a firstreactive material comprising, consisting essentially of, or consistingof TiCl₄, and a second reactive material comprising, consistingessentially of, or consisting of H₂.

In yet other exemplary processing, the mass 16 can comprise, consistessentially of, or consist of SiO₂; and can be formed from a firstsilicon-containing reactive material and a second reactive materialcomprising oxygen. The first silicon-containing material can comprise,consist essentially of, or consist of, for example, silane ortrichlorosilane. The oxygen-containing reactive material can comprise,consist essentially of, or consist of one or more of O₂, O₃, and H₂O₂.

In yet another embodiment, mass 16 can comprise Al₂O₃, and can be formedfrom a first reactive material comprising, consisting essentially of, orconsisting of Al(CH₃)₃, and a second reactive material comprising,consisting essentially of, or consisting of H₂O.

In another exemplary embodiment, mass 16 can comprise, consistessentially of, or consist of ZrO, with the composition being shown interms of the elements contained therein rather than in terms of astoichiometric relationship of the elements (typically the compositionwould be ZrO₂). In such embodiment, the first reactive material cancomprise, consist essentially of, or consist of ZrCl₄, and the secondreactive material can comprise, consist essentially of, or consist ofH₂O.

In another exemplary embodiment, the mass 16 can comprise, consistessentially of, or consist of HfO, with the listed composition beingshown sin terms of the elements contained therein rather than in termsof a stoichiometric relationship of the elements (typically thecomposition would be HfO₂). The first reactive material can comprise,consist essentially of, or consist of HfCl₄, and the second reactivematerial can comprise, consist essentially of, or consist of H₂O.

In yet other exemplary embodiments, various cycles of ALD can beutilized to incorporate mass 16 into a laminate comprising Al₂O₃ andtantalum, or a laminate comprising Al₂O₃ and one or more of Ta₂O₅, HfO₂,ZrO₂ and SiO₂. Alternatively, mass 16 can be incorporated into alaminate consisting essentially of Al₂O₃ and SiO₂.

In particular aspects, the invention pertains to methods in which aplurality of discrete semiconductor substrates are simultaneouslysubjected to ALD within a common reaction chamber. Such aspects aredescribed with reference to an exemplary apparatus 50 in FIG. 4.Apparatus 50 comprises a reaction chamber 52. Chamber 52 has a top 54, abottom 56, a first vertical segment 58, and a second vertical segment60. First vertical segment 58 is in opposing relation relative to secondvertical segment 60, and top 54 is in opposing relation relative tobottom 56. Chamber 52 can comprise a cylindrical shape such that sides58 and 60 are part of a common curved lateral periphery of the chamber.Alternatively, chamber 52 can comprise a rectangular or square shape.

Chamber 52 comprises a wall 61 which defines a periphery of the chamber.An inlet port 62 extends through wall 61 at bottom 56 of the chamber,and an outlet port 64 extends through wall 61 at top 54 of the chamber.Top 54 and bottom 56 can be considered to be sides of chamber 52 (i.e.,a top side and a bottom side) which are opposed relative to one another,and can be referred to as a first sidewall and second sidewall,respectively.

Inlet 62 is in fluid communication with a source 66 of first reactivematerial, and a source 68 of second reactive material. Materials fromsources 66 and 68 flow through a valve 70 and into chamber 52 along thedirection designated by arrow 72. Valve 70 is preferably configured toallow only one of the reactive materials to flow into chamber 52 at anygiven time. Accordingly, apparatus 50 is configured for utilization inan ALD process, rather than a CVD process. The shown configuration ofhaving two reaction components configured to flow through a single valve70 into chamber 52 is an exemplary embodiment, and an apparatus of thepresent invention can have other configurations. For instance, more thantwo sources of reactive gases can be in fluid communication with inletport 62 through a valve. Further, multiple valves can be utilized sothat each reactive component flows through a separate valve relative tothe other reactive components. Additionally, a source of purge gas canbe provided in fluid communication with inlet 62 to simplify purging ofa first reactive material from within chamber 52 prior to introductionof a second reactive material into the chamber.

Outlet port 64 is in fluid communication through a valve 72 with a pump74. Pump 74 can be utilized to evacuate chamber 52 prior to introductionof a reactive material into the chamber, as well as to rapidly pullreactive materials through the chamber.

A plurality of heating coils 76 are shown extending around chamber 52.Coils 76 can be utilized to heat chamber wall 61 during an ALDoperation. Such can reduce or eliminate side reactions from occurringrelative to wall 61. The side reactions can be problematic if wall 61 iscold relative to semiconductor substrate surfaces which are beingtreated within chamber 52, as many of the reactive components utilizedin ALD can react at or near cold chamber walls. Construction 50 can beconsidered a furnace due to the inclusion of heating elements 76 withinthe construction.

A holder 80 is provided within chamber 52, and such retains a pluralityof semiconductor substrates 82. The substrates 82 are shown withcross-hatching to assist the reader in visualizing the structures, andnot to indicate any conductivity or material compositions of thestructures. Each of the substrates 82 can be considered as beingdiscrete relative to the other substrates 82 retained within thechamber.

Holder 80 comprises legs 84 which elevate a base of holder 80 above aninternal bottom surface of wall 61. Various additional heating elements(not shown) can be included within construction 50 to heat theindividual semiconductor substrates 82 retained within the chamber.

In operation, a plurality of discrete semiconductor substrates areprovided within chamber 52, and subsequently a first reactive materialis flowed into the chamber. At least some of the exposed surfaces of thediscrete semiconductor substrates react with the first reactive materialso that a layer (typically a monolayer) is formed over at least some ofthe exposed surfaces. In particular embodiments, all of the exposedsurfaces of the semiconductor substrates have a monolayer formedthereover. In such embodiments, back surfaces of the semiconductorsubstrates can be retained within a protective structure so that themonolayer is not formed on such back surfaces. The monolayer can beconsidered as a first mass formed across the exposed surfaces of theplurality of discrete semiconductor substrates. The substrates arepreferably held at a first temperature during the exposure to the firstreactive material. An exemplary temperature can be from about 300° C. toabout 700° C. Such temperature can be particularly useful inapplications in which the first reactive material is asilicon-containing precursor, such as, for example, trichlorosilane.

Substrates 82 can be exposed to the reactive material for a sufficienttime to saturate exposed surfaces of the substrates with a desired mass.For instance, if the substrates are exposed to a silicon-containingreactive precursor to form a silicon-containing mass, the substrateswill preferably be exposed for a sufficient time to saturate exposedsurfaces of the substrates with the silicon-containing mass. If thesilicon-containing precursor comprises trichlorosilane, and the exposedsurfaces comprised silicon, a suitable exposure time can be at leastabout 5 minutes.

After the exposure of substrates 82 to the first reactive material, pump74 can be utilized to evacuate the first reactive material from withinchamber 52. A purge gas can be flushed through the chamber during suchevacuation.

After the first reactive material is purged from within chamber 52, asecond reactive material is introduced into the chamber. The secondreactive material converts the first mass into a second mass. In anexemplary embodiment in which the first mass is formed fromtrichlorosilane, the second reactive material can comprise anitrogen-containing precursor, such as, for example, ammonium, toconvert the first mass into silicon nitride.

It can be preferred that the discrete semiconductor substrates are heldat a temperature during exposure to the second reactive material whichis comparable to the temperature utilized during exposure to the firstreactive material. In particular embodiments, the semiconductorsubstrates can be held at a temperature during exposure to the secondreactive material which is within about 100° C. of the temperatureutilized during exposure to the first reactive material, within about50° C. of the temperature utilized during exposure to the first reactivematerial, within about 25° C. of the temperature utilized during thefirst reactive material, within about 10° C. of the temperature utilizedduring exposure to the first reactive material, within about 5° C. ofthe temperature utilized during exposure to the first reactive material,or even within about 1° C. of the temperature utilized during exposureto the first reactive material.

An advantage of utilizing about the same temperature during exposure ofsubstrates 82 to the second reactive material as is utilized duringexposure to the first reactive material is that such can simplify athermal cycle utilized during an ALD process. An additional advantage isthat substrates 82 will not be exposed to substantially differentthermal temperatures during the ALD process, which can alleviateformation of thermally-induced defects within substrates 82.

Heating elements 76 can be utilized to ensure that reaction chamber 52has hot internal walls during exposure of the discrete semiconductorsubstrates to the first and second reactive materials, and specificallyto ensure that the internal wall temperature is about the same as thetemperature of the semiconductor substrates during exposure to the firstand second reactive materials. If the internal wall temperature is aboutthe same as the temperature of the substrates during exposure to thefirst and second reactive materials, such can alleviate or eliminategeneration of contaminates within chamber 52. Further, to the extentthat side reactions occur at the walls of chamber 52, such reactionswill be occurring at the same temperature as substrates 82 are exposedto, and accordingly the side reactions can generate the same materialsas are being deposited on substrates 82. Thus, if the materials from theside reactions inadvertently fall from walls of chamber 52 onto thesubstrates, they may simply be additional desired material on thesubstrates rather than contaminating material.

The exemplary pressure within chamber 52 during exposure of substrates82 to the first and second reactive materials is typically at leastabout 1 Torr, and can be equal to or greater than atmospheric pressure.

An advantage of utilizing the chamber construction 52 of FIG. 4 is thatsuch can enable rapid flushing of a chamber between ALD cycles, as wellas rapid ramping of a pressure within the chamber to a desired levelwhen filling the chamber with reactive material. Chamber 52 can beconsidered to comprise an upper sidewall 54 having a first internalsurface area. Outlet port 64 extends through upper sidewall 54, and thusreduces the internal surface area of the sidewall. In other words, thereis less of sidewall 54 present due to the opening of outlet 64 thanthere would be if there was no opening of outlet 64. The size of outlet64 is preferably large enough relative to sidewall 54 to enable rapidflushing of materials from within chamber 52. Accordingly, outlet port64 preferably reduces an internal surface area of sidewall 54 by atleast about 30 percent, more preferably by at least about 50 percent,yet more preferably by at least about 70 percent, and even morepreferably by at least 90 percent.

Similarly, inlet port 62 reduces an internal surface area of sidewall56, and preferably inlet port 62 is large enough relative to sidewall 56to enable rapid transfer of reactive materials into chamber 52.Accordingly, inlet port 62 preferably reduces an internal surface areaof sidewall 56 by at least about 30 percent, more preferably by at leastabout 50 percent, yet more preferably by at least about 70 percent, andeven more preferably by at least about 90 percent.

In a particular aspect of the invention, the relative size of inlet port62 and/or outlet port 64 to chamber 52 can be adjustable.

In exemplary embodiments, methodology of the present invention caninclude various pretreatments of semiconductor substrates within areaction chamber prior to an ALD process occurring in the same reactionchamber. For instance, semiconductor substrates containing silicon willfrequently have native oxide (SiO₂) formed thereover. Such native oxidecan be problematic in various semiconductor constructions, andaccordingly it can be desired to remove the native oxide prior to an ALDprocess. In particular methodology of the present invention, a pluralityof substrates 82 are provided within a reaction chamber 52, and thesubstrates are exposed to one or more of H, F, and Cl to remove nativeoxide from the semiconductor substrates. After the native oxide isremoved, the substrates are exposed to an ALD process within thechamber, which comprises exposure of the substrates to a first reactivematerial, purging of the first reactive material from within thechamber, and subsequent exposing of the substrates to a second reactivematerial.

The removal of the native oxide can comprise, for example, exposing thesemiconductor substrates to H₂ at a temperature of at least about 750°C. Alternatively, the native oxide removal can comprise exposing thesemiconductor substrates to at least one plasma-activated species ofhydrogen. Such plasma-activated species of hydrogen can be introducedinto chamber 52 through a separate port (not shown). The separate portcan be in fluid communication with a reaction chamber (not shown) inwhich one or more hydrogen-containing precursors are exposed to plasmato generate plasma-activated species of hydrogen. The plasma-activatedhydrogen-containing species are the fed through the separate port intoreaction chamber 52.

Alternatively, the removal of native oxide can comprise exposing thesemiconductor substrates to gaseous HCl and/or HF within chamber 52.

In another exemplary pretreatment of semiconductor substrates, thesubstrates can be exposed to oxygen within chamber 52 to form a uniformlayer of oxide across exposed oxidizable surfaces of silicon-containingsemiconductor substrates prior to an ALD process. Such can beaccomplished by, for example, placing a plurality of semiconductorsubstrates 82 within chamber 52, and subsequently exposing thesubstrates to a source of oxygen comprising, consisting of, orconsisting essentially of one or more of O₂, O₃, and H₂O₂. Afterexposure to the oxygen, the reaction chamber 52 can be flushed andsubsequently substrates 82 are subjected to an ALD process.

The formation of a uniform layer of oxide over exposed oxidizablesurfaces of the substrates can provide a homogeneous base for subsequentformation of materials by ALD.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. An atomic layer deposition method for treating semiconductorsubstrates, comprising: providing a reaction chamber having a top, abottom, and sidewalls connecting the top and the bottom; placing a stackof discrete semiconductor substrates within the reaction chamber, atleast a portion of the substrates having surfaces comprising nativeoxide, wherein the stack comprises a bottom substrate defining thebottom of the stack and a top substrate defining the top of the stack;exposing the stack to H₂ at a temperature of at least about 750° C. toremove at least a portion of the native oxide from the surfaces, whereinduring the exposing, the bottom of the stack is exposed to the H₂ beforethe top of the stack is exposed to the H₂; exposing the stack to a firstreactive material to form a first mass over at least some of thesurfaces of the semiconductor substrates; and exposing the stack to asecond reactive material to convert the first mass to a second mass. 2.The method of claim 1 wherein the exposing the stack to the H₂ comprisesexposing the stack to at least one plasma-activated species of hydrogen.3. The method of claim 1 wherein the reaction chamber has hot internalwalls during the exposing of the stack to the first and second reactivematerials.
 4. The method of claim 1 wherein the second mass is TaO; withthe composition being shown in terms of the elements contained thereinrather than in terms of a stoichiometric relationship of the elements.5. The method of claim 1 wherein the second mass comprises Ta.
 6. Themethod of claim 1 wherein the placing the stack comprises verticallystacking a plurality of discrete semiconductor substrates within thereaction chamber.
 7. The method of claim 1 wherein the second masscomprises W.
 8. The method of claim 1 wherein the second mass comprisesAl.
 9. The method of claim 1 wherein the second mass comprises Hf. 10.The method of claim 1 wherein the second mass comprises Zr.
 11. Themethod of claim I wherein the second mass comprises SiO, with thecomposition being shown in terms of the elements contained thereinrather than in terms of a stoichiometric relationship of the elements.12. The method of claim 1 wherein the second mass comprises SiN, withthe composition being shown in terms of the elements contained thereinrather than in terms of a stoichiometric relationship of the elements.13. The method of claim 1 wherein: the second mass comprises SIN, withthe composition being shown in terms of the elements contained thereinrather than in terms of a stoichiometric relationship of the elements;and the second mass is exposed to oxygen to form SiON from the SiN, withthe composition SiON being shown in terms of the elements containedtherein rather than in terms of a stoichiometric relationship of theelements.
 14. The method of claim 13 wherein the exposure to oxygencomprises exposure to one or more of O₂, O₃ and H₂O_(2.)
 15. The methodof claim 1 wherein the placing the stack comprises vertically stacking aplurality of discrete semiconductor substrates within the reactionchamber.
 16. The method of claim 1 wherein the exposing the stack to theH₂ comprises providing the H₂ to a location with the reaction chamberproximate the bottom of the reaction chamber.
 17. The method of claim 1wherein the exposing the stack to the H₂ comprises providing the H₂ to alocation within the reaction chamber below the bottom of the stack. 18.The method of claim 1 further comprising, after exposing the stack tothe H₂, removing the H₂ from the chamber, wherein the removing the H₂from the chamber comprises removing the H₂ from a location within thechamber proximate the top of the reaction chamber.
 19. The method ofclaim 18 wherein the removing the H₂ from the chamber comprises removingthe H₂ from a location within the chamber above the top of the stack.20. The method of claim 1 wherein: the exposing the stack to the H₂comprises providing the H₂ to a location within the chamber below thebottom of the stack; and further comprises, after exposing the stack tothe H₂, removing the H₂ from the chamber, wherein the removing the H₂from the chamber comprises removing the H₂ from a location within thechamber above the top of the stack.